basic(+PasswordFile)

Use HTTP Basic authetication and verify the password from PasswordFile. PasswordFile is a file holding usernames and passwords in a format compatible to Unix and Apache. Each line is record with : separated fields. The first field is the username and the second the password hash. Password hashes are validated using crypt/2.

Successful authorization is cached for 60 seconds to avoid overhead of decoding and lookup of the user and password data.

http_authenticate/3 just validates the header. If authorization is not provided the browser must be challenged, in response to which it normally opens a user-password dialogue. Example code realising this is below. The exception causes the HTTP wrapper code to generate an HTTP 401 reply.

(   http_authenticate(basic(passwd), Request, Fields)
->  true
;   throw(http_reply(authorise(basic, Realm)))
).

To be done

Should we also cache failures to reduce the risc of DoS attacks?